参考资料：B站狂神教程
https://www.bilibili.com/video/BV1og4y1q7M4?p=36
Docker的网络模式
root@KitDevVps:~# docker network ls
NETWORK ID NAME DRIVER SCOPE
1375b7ef4bbc bridge bridge local
b29eab4db971 host host local
acfcd6eaf888 none null local
有以下几种网络模式：
- bridge：桥接（docker默认）
- none：不配置网络
- host：和宿主机共享网络
- container：容器网络连通（用的很少，不建议使用，局限性很大）
我们自己创建网络，也是用bridge桥接模式。
创建网络
自己创建网络的命令是docker network create。
我们每次run出容器的时候，默认使用bridge模式，run的命令中默认有--net bridge这么一个选项。因为bridge是docker0的Name。我们自己创建网络的时候就应该避开bridge这个名字。假如我们自己create的网络叫bridge02，我们想让自己的容器加入这个网络的时候，run的时候就加上--net bridge02就可以了。
我们看一下docker network create这个命令怎么用：
root@KitDevVps:~# docker network create -h
Flag shorthand -h has been deprecated, please use --help
Usage: docker network create [OPTIONS] NETWORK
Create a network
Options:
--attachable Enable manual container attachment
--aux-address map Auxiliary IPv4 or IPv6 addresses used by Network driver (default map[])
--config-from string The network from which copying the configuration
--config-only Create a configuration only network
-d, --driver string Driver to manage the Network (default "bridge")
--gateway strings IPv4 or IPv6 Gateway for the master subnet
--ingress Create swarm routing-mesh network
--internal Restrict external access to the network
--ip-range strings Allocate container ip from a sub-range
--ipam-driver string IP Address Management Driver (default "default")
--ipam-opt map Set IPAM driver specific options (default map[])
--ipv6 Enable IPv6 networking
--label list Set metadata on a network
-o, --opt map Set driver specific options (default map[])
--scope string Control the network's scope
--subnet strings Subnet in CIDR format that represents a network segment
其中的subnet子网一定要配，加上掩码；driver默认就是bridge模式，写不写都行；gateway也写一下，就是网关，网络从哪个地方出去。我们模仿路由器配一个：
root@KitDevVps:~# docker network create --driver bridge --subnet 192.168.0.0/16 --gateway 192.168.0.1 mynet
0df835de9886ed3cf76b071281ddc521c33502914aeb69a8e1bbc817dbcdff0a
其中网段192.168.0.0，掩码位数16.也就是有255*255个ip可用。如果是24的话就只有255个ip可用，这一块是计算机网络的知识。网关是192.168.0.1。网络取名为mynet。
用docker network ls看一下我们的网络有没有：
root@KitDevVps:~# docker network ls
NETWORK ID NAME DRIVER SCOPE
1375b7ef4bbc bridge bridge local
b29eab4db971 host host local
0df835de9886 mynet bridge local
acfcd6eaf888 none null local
已经有了，在倒数第二行。看一下网络的详细信息：
root@KitDevVps:~# docker network inspect mynet
[
{
"Name": "mynet",
"Id": "0df835de9886ed3cf76b071281ddc521c33502914aeb69a8e1bbc817dbcdff0a",
"Created": "2020-07-05T09:39:03.14488529Z",
"Scope": "local",
"Driver": "bridge",
"EnableIPv6": false,
"IPAM": {
"Driver": "default",
"Options": {},
"Config": [
{
"Subnet": "192.168.0.0/16",
"Gateway": "192.168.0.1"
}
]
},
"Internal": false,
"Attachable": false,
"Ingress": false,
"ConfigFrom": {
"Network": ""
},
"ConfigOnly": false,
"Containers": {},
"Options": {},
"Labels": {}
}
]
可以看到子网和网关都是我们自己配置的，没有问题。
我们启动两个centos容器，放在这个网络里：
root@KitDevVps:~# docker run -d -it --name centos01 --net mynet centos
43f47db12bf4a8be9ea6172a89a44c530a23b29de49bf2a5ef95a88308675025
root@KitDevVps:~# docker run -d -it --name centos02 --net mynet centos
2a26067838f1724347ef50a1b8988a50603715e514fb288ab86401571dc70173
root@KitDevVps:~# docker ps
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES
2a26067838f1 centos "/bin/bash" 7 seconds ago Up 6 seconds centos02
43f47db12bf4 centos "/bin/bash" 16 seconds ago Up 15 seconds centos01
1cdd55fd90c5 nginx "/docker-entrypoint.…" 2 days ago Up 2 days 0.0.0.0:80->80/tcp nginx1
再看一下mynet的详细信息：
root@KitDevVps:~# docker network inspect mynet
[
...
"Containers": {
"2a26067838f1724347ef50a1b8988a50603715e514fb288ab86401571dc70173": {
"Name": "centos02",
"EndpointID": "83e59d8f388561cb006564de55bb1c76278ab54b0e87f1f7e671a9962efe3608",
"MacAddress": "02:42:c0:a8:00:03",
"IPv4Address": "192.168.0.3/16",
"IPv6Address": ""
},
"43f47db12bf4a8be9ea6172a89a44c530a23b29de49bf2a5ef95a88308675025": {
"Name": "centos01",
"EndpointID": "b0a1f17acc6a4c835952ae4e764c7f7e26a90fc3ce28be97cf9bb8c2ee0c10a4",
"MacAddress": "02:42:c0:a8:00:02",
"IPv4Address": "192.168.0.2/16",
"IPv6Address": ""
}
},
"Options": {},
"Labels": {}
]
可以看到containers中有了我们的两个容器，他们的ip地址也是这个网段的。
使用容器名代替ip地址来ping
自己创建网络有什么好处呢，好处就是可以直接使用容器名来互ping：
root@KitDevVps:~# docker exec -it centos01 ping centos02
PING centos02 (192.168.0.3) 56(84) bytes of data.
64 bytes from centos02.mynet (192.168.0.3): icmp_seq=1 ttl=64 time=0.099 ms
64 bytes from centos02.mynet (192.168.0.3): icmp_seq=2 ttl=64 time=0.167 ms
64 bytes from centos02.mynet (192.168.0.3): icmp_seq=3 ttl=64 time=0.079 ms
64 bytes from centos02.mynet (192.168.0.3): icmp_seq=4 ttl=64 time=0.090 ms
^C
--- centos02 ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 45ms
rtt min/avg/max/mdev = 0.079/0.108/0.167/0.036 ms
即现在不使用--link也可以连接成功了。
我们自定义的网络，docker帮我们维护好了对应的关系，docker0则没有这个功能。
比如我有一个redis的集群，就可以打一个网络。还有一个mssql的集群，也可以搭一个网络。网络之间是互相隔离的。不同集群使用不同网络，集群都是健康的。
多个网络之间的连通
docker0网络中的一个容器如何访问mynet网络？显然也要通过docker network命令来找线索：
root@KitDevVps:~# docker network -h
Flag shorthand -h has been deprecated, please use --help
Usage: docker network COMMAND
Manage networks
Commands:
connect Connect a container to a network
create Create a network
disconnect Disconnect a container from a network
inspect Display detailed information on one or more networks
ls List networks
prune Remove all unused networks
rm Remove one or more networks
Run 'docker network COMMAND --help' for more information on a command.
可以看到第一条命令connect，介绍是连接一个容器到一个网络。看一下这个命令怎么用：
root@KitDevVps:~# docker network connect -h
Flag shorthand -h has been deprecated, please use --help
Usage: docker network connect [OPTIONS] NETWORK CONTAINER
Connect a container to a network
Options:
--alias strings Add network-scoped alias for the container
--driver-opt strings driver options for the network
--ip string IPv4 address (e.g., 172.30.100.104)
--ip6 string IPv6 address (e.g., 2001:db8::33)
--link list Add link to another container
--link-local-ip strings Add a link-local address for the container
root@KitDevVps:~#
显然用法就是docket network connect [可选选项] 网络 容器。现在我们有centos01和02运行在mynet上，我们在docker0上run出个centos03：
root@KitDevVps:~# docker exec -it centos03 ping centos01
ping: centos01: Name or service not known
root@KitDevVps:~# docker exec -it centos03 ping 43f47db12bf4
ping: 43f47db12bf4: Name or service not known
可以看到无论ping名还是id都ping不通。试一下前面我们查到的命令：
root@KitDevVps:~# docker network connect mynet centos03
root@KitDevVps:~# docker exec -it centos03 ping centos01
PING centos01 (192.168.0.2) 56(84) bytes of data.
64 bytes from centos01.mynet (192.168.0.2): icmp_seq=1 ttl=64 time=0.163 ms
64 bytes from centos01.mynet (192.168.0.2): icmp_seq=2 ttl=64 time=0.081 ms
64 bytes from centos01.mynet (192.168.0.2): icmp_seq=3 ttl=64 time=0.104 ms
64 bytes from centos01.mynet (192.168.0.2): icmp_seq=4 ttl=64 time=0.107 ms
^C
--- centos01 ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 46ms
rtt min/avg/max/mdev = 0.081/0.113/0.163/0.032 ms
运行docker network connect mynet centos03后没有返回东西，但centos03已经可以ping通centos01了，而且还是用容器名字直接ping通。
我们看一下mynet的详细信息：
root@KitDevVps:~# docker network inspect mynet
[
...
"Containers": {
"2a26067838f1724347ef50a1b8988a50603715e514fb288ab86401571dc70173": {
"Name": "centos02",
"EndpointID": "83e59d8f388561cb006564de55bb1c76278ab54b0e87f1f7e671a9962efe3608",
"MacAddress": "02:42:c0:a8:00:03",
"IPv4Address": "192.168.0.3/16",
"IPv6Address": ""
},
"43f47db12bf4a8be9ea6172a89a44c530a23b29de49bf2a5ef95a88308675025": {
"Name": "centos01",
"EndpointID": "b0a1f17acc6a4c835952ae4e764c7f7e26a90fc3ce28be97cf9bb8c2ee0c10a4",
"MacAddress": "02:42:c0:a8:00:02",
"IPv4Address": "192.168.0.2/16",
"IPv6Address": ""
},
"62bad532ae1925a4a33388f629931b573bcd1b6fd00e9ab5b99799dbdb17c73b": {
"Name": "centos03",
"EndpointID": "763c6c021ae7a05d3099d6c64c3dd28b1a574ecbf46e2689441e17afccc58da6",
"MacAddress": "02:42:c0:a8:00:04",
"IPv4Address": "192.168.0.4/16",
"IPv6Address": ""
}
},
"Options": {},
"Labels": {}
]
可以看到centos03直接被加入到了mynet这个网络里。这样centos03这个容器就拥有了两个ip地址，它在docker0中有一个，在mynet中还有一个。
centos01能ping通centos03吗？
root@KitDevVps:~# docker exec -it centos01 ping centos03
PING centos03 (192.168.0.4) 56(84) bytes of data.
64 bytes from centos03.mynet (192.168.0.4): icmp_seq=1 ttl=64 time=0.067 ms
64 bytes from centos03.mynet (192.168.0.4): icmp_seq=2 ttl=64 time=0.081 ms
64 bytes from centos03.mynet (192.168.0.4): icmp_seq=3 ttl=64 time=0.077 ms
64 bytes from centos03.mynet (192.168.0.4): icmp_seq=4 ttl=64 time=0.092 ms
^C
--- centos03 ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 42ms
rtt min/avg/max/mdev = 0.067/0.079/0.092/0.010 ms
02能ping通03吗？
root@KitDevVps:~# docker exec -it centos02 ping centos03
PING centos03 (192.168.0.4) 56(84) bytes of data.
64 bytes from centos03.mynet (192.168.0.4): icmp_seq=1 ttl=64 time=0.094 ms
64 bytes from centos03.mynet (192.168.0.4): icmp_seq=2 ttl=64 time=0.127 ms
64 bytes from centos03.mynet (192.168.0.4): icmp_seq=3 ttl=64 time=0.100 ms
64 bytes from centos03.mynet (192.168.0.4): icmp_seq=4 ttl=64 time=0.115 ms
^C
--- centos03 ping statistics ---
4 packets transmitted, 4 received, 0% packet loss, time 53ms
rtt min/avg/max/mdev = 0.094/0.109/0.127/0.012 ms
其实后面这两次都是废话，都在同一个网络里了当然能ping通，而且ping的地址是03在mynet中的地址，不是在docker0中的地址。玩这两次只是为了100%确定这个结论。